BACKGROUND Global plastic use has consistently increased over the past century with several different types of plastics now being produced. Much of these plastics end up in oceans or landfills leading to a substantial accumulation of plastics in the environment. Plastic debris slowly degrades into microplastics (MPs) that can ultimately be inhaled or ingested by both animals and humans. A growing body of evidence indicates that MPs can cross the gut barrier and enter into the lymphatic and systemic circulation leading to accumulation in tissues such as the lungs, liver, kidney, and brain. The impacts of mixed MPs exposure on tissue function through metabolism remains largely unexplored. OBJECTIVES This study aims to investigate the impacts of polymer microspheres on tissue metabolism in mice by assessing the microspheres ability to translocate across the gut barrier and enter into systemic circulation. Specifically, we wanted to examine microsphere accumulation in different organ systems, identify concentration-dependent metabolic changes, and evaluate the effects of mixed microsphere exposures on health outcomes. METHODS To investigate the impact of ingested microspheres on target metabolic pathways, mice were exposed to either polystyrene (5μm) microspheres or a mixture of polymer microspheres consisting of polystyrene (5μm), polyethylene (1-4μm), and the biodegradability and biocompatible plastic, poly-(lactic-co-glycolic acid) (5μm). Exposures were performed twice a week for 4 weeks at a concentration of either 0, 2, or 4mg/week via oral gastric gavage. Tissues were collected to examine microsphere ingress and changes in metabolites. RESULTS In mice that ingested microspheres, we detected polystyrene microspheres in distant tissues including the brain, liver, and kidney. Additionally, we report on the metabolic differences that occurred in the colon, liver, and brain, which showed differential responses that were dependent on concentration and type of microsphere exposure. DISCUSSION This study uses a mouse model to provide critical insight into the potential health implications of the pervasive issue of plastic pollution. These findings demonstrate that orally consumed polystyrene or mixed polymer microspheres can accumulate in tissues such as the brain, liver, and kidney. Furthermore, this study highlights concentration-dependent and polymer type-specific metabolic changes in the colon, liver, and brain after plastic microsphere exposure. These results underline the mobility within and between biological tissues of MPs after exposure and emphasize the importance of understanding their metabolic impact. https://doi.org/10.1289/EHP13435.

中文翻译：

---

聚苯乙烯或混合聚合物微球的体内组织分布以及小鼠口服暴露后的代谢组学分析。


背景技术在过去的一个世纪中，全球塑料的使用量持续增加，现在正在生产几种不同类型的塑料。这些塑料大部分最终进入海洋或垃圾填埋场，导致塑料在环境中大量积累。塑料碎片慢慢降解成微塑料 (MP)，最终可以被动物和人类吸入或摄入。越来越多的证据表明，MP 可以穿过肠道屏障，进入淋巴和体循环，导致在肺、肝、肾和脑等组织中积累。混合 MP 暴露对代谢组织功能的影响在很大程度上尚未得到探索。目的 本研究旨在通过评估微球穿过肠道屏障并进入体循环的能力，研究聚合物微球对小鼠组织代谢的影响。具体来说，我们想要检查微球在不同器官系统中的积累，确定浓度依赖性代谢变化，并评估混合微球暴露对健康结果的影响。方法 为了研究摄入的微球对目标代谢途径的影响，将小鼠暴露于聚苯乙烯（5μm）微球或由聚苯乙烯（5μm）、聚乙烯（1-4μm）以及生物可降解性和生物相容性塑料组成的聚合物微球混合物，聚（乳酸-乙醇酸）（5μm）。通过口服胃饲法以 0、2 或 4 毫克/周的浓度每周进行两次暴露，持续 4 周。收集组织以检查微球的进入和代谢物的变化。 结果在摄入微球的小鼠中，我们在远处组织（包括大脑、肝脏和肾脏）中检测到了聚苯乙烯微球。此外，我们报告了结肠、肝脏和大脑中发生的代谢差异，这些差异显示出取决于微球暴露的浓度和类型的不同反应。讨论 这项研究使用小鼠模型来深入了解普遍存在的塑料污染问题对健康的潜在影响。这些发现表明，口服聚苯乙烯或混合聚合物微球可以在脑、肝和肾等组织中积累。此外，这项研究强调了塑料微球暴露后结肠、肝脏和大脑中浓度依赖性和聚合物类型特异性的代谢变化。这些结果强调了暴露后 MP 生物组织内和生物组织之间的流动性，并强调了了解其代谢影响的重要性。 https://doi.org/10.1289/EHP13435。